Equipment for applying tape in a C-clip configuration are very well known and are commonplace in the literature and the industry A conventional taping machine uses a conveying system to advance the carton through the tape applicators positioned to apply a strip of tape from a roll of tape to the carton from the top, the bottom or the side with different speeds under different carton packaged conditions such as empty, over-filled or under-filled cartons. Such applicators generally apply a continuous ribbon of tape onto a leading face of a case or carton passing through the machine, along the surface of the case facing the taper and at least partway along the trailing face of the case i.e. the ribbon of tape forms a C-shape. The tape is applied against the leading face using a front applicator which holds the tape to top (assuming a tape application to the top of a case or carton) and then applied against the trailing face of the case using a rear tape applicator. The applicators are usually in the form roll but sometimes the roll is replaced with a wiper.
Common problems in carton taping include loosely wrinkled tape left on the taped carton; flagging at the rear corner; tape not making sufficient surface contact to adhere to the carton particularly in soft, under-packed or un-even surfaces carton conditions. Conventional tape applicators generally rely on the front application or wipe down roller to apply pressure on the tape to the top of the carton and a brush located at the discharge end of the tape applicator for tape wiping action. (See for example U.S. Pat. Nos. 4,738,075; 4,889,581; 5,223,075 and/or 7,836,932). The rear applicator or roller is linked to the front roller by a push bar and a spring biases these rolls toward the case being taped, the rear roller pressure is affected by the spring tension and drag from the up-stream tape path including force required to pull the tape from the tape supply roll and the preset tension required for tape cutting and, friction generated by the rollers. When the resisting tape tension increased or a light spring force setting is being used for soft carton, the tape will pull the front and the rear rollers away from the surface of the carton, reducing the application pressure or completely losing surface contact between the tape and the carton, with insufficient tape adhesion to the carton during the application process, the tape cut off with a sudden release of tension causing the tape to snap back with wrinkled, misaligned or crumpled tape placement on the carton which is being brush down by a brush further down the end of the tape applicator. In most common situations the trailing cut-off end of the tape snap backs and the adjacent adhesive surfaces stick together (referred to in the art as flagging, crumpling) around the rear corner of the carton, surface of the causing a defective sealing closure between the flaps and the vertical carton.
US publication no 2008-0264571 dated Oct. 30, 2008 applicant Lam discloses a wiper element mounted on the front applicator arm and functioning as a front applicator for providing access to a cutter positioned behind it to cut a leading end of a newly threaded tape and to wipe the tape as it is being applied onto the carton or case being sealed by the tape. This wiper mounted on the front applicator arm aggravated the above-mentioned problem because the tape generated more friction around the end of the wiper that in many cases dragged the wiper away from the taping surface.
In conventional taping devices at the point of cutting, the contact with the tape and the tip of the blade is almost at a right angle. When a serrated blade is used the teeth of the serrated blade penetrate through the thickness of the tape, resulting in the tip of the teeth puncturing the tape at contact and wedging the tape to the bottom of the teeth, as a result, any adhesive or loose debris of tape from the cutting may wedged in between the bottom of the teeth, consolidated and slowly build up. As a result it is common practice to provide an oil pad attached to the blade cover to lubricate the cutting blade to minimize the amount of build-up, however, it still requires periodically cleaning. Otherwise it will affect the tape cutting causing production down-time. U.S. Pat. No. 6,553,884 illustrates an attempt to overcome this problem. Another problem with conventional tape applicators is related to holding and guiding the end of the tape in position for application to the leading end of a case or carton being taped. Since the leading portion of the tape has to be apply onto the vertical surface of the carton, the front application roller and the leading end of the tape has to protrude into a position to face the incoming carton to allow the adhesive surface of leading end of the tape to make contact with the carton.
The leading end of the tape commonly is intended to stay on to the surface of the front application roller using static charges generated by previous movement and friction on the non-adhesive surface of the tape. This is not reliable especially when taping the bottom of a case or carton, the tape often falls off the application roller and misses the carton.
Many mechanical devises are being used to retain the leading portion of the tape to prevent the falling of the tape as well as forming the tape from both side or in the middle of the tape in order to make the tape more rigid and thereby hold its position relative to the surface of the application roller, those devises are complicated which makes tape threading difficult, most importantly, they are not effective when a short tab length application is required i.e. a short tab has a leading end of the tape that is not long enough to reach the surface of the application roller. The short leading end of the tape is captured inside the retaining guides or a U sharp bracket, preventing the tape to contact the carton (see for example U.S. Pat. Nos. 4,642,157 and/or 7,836,932).
U.S. Pat. No. 5,725,721 provides an example of a device that can hold and expose the short leading end of the tape however, it does not provide a full surface support at the back of the tape to sufficiently presses the tape onto the carton surface and the tape will just smear the surface of the carton without adhesion so that the entire taping process is in effective.
In most cases, lacking full backing support of the short leading end of the tape causes the tape partially adhered onto the vertical surface of the carton, the corner of the carton may help to pull and advance the tape from up-stream to complete the taping process however, the taped carton is defective with insufficient adhesion of the front tab having the flaps loosely taped around the shoulder of the carton.
In carton taping, the tape is applied to the top (or bottom) and along the leading a trailing ends of the carton to form a U shape, commonly call C clip. The two ends (tabs) of the tape each extend from their adjacent corner of the carton and extend along the front and back vertical surfaces of the case respectively. Longer tabs are used for larger and heavier cases, shorter tabs are adjusted for shallower or smaller and lighter cases. The vertical tab length of the trailing end of the carton can be set commonly by an adjustable bar attached at the tip of the cutting cam, extend the bar to delay the cutting for longer tab length, retract the bar to release the cam sooner to shorten the tab length.
The front tab length adjustment is commonly achieved by adjusting the tension on the one way clutch roller with less tension for longer tab length and more tension for shorter tab length. This method is not very effective as the changes in tape tension can create problems in tape adhesion and tape cutting. Other tape applicator adjusts the mounting position of the one way clutch roller on the frame which controls the amount a tape length to pull back after the tape cutting when the front arm swings back from the retracted cutting position to the normal extended position. The more tape pulled back, shorter tape is exposed on the front application roller to tape the incoming vertical surface of the leading or front panel of oncoming carton;
The less tape pulled back, longer tape tab left to be applied on the front panel. Moving the one way clutch roller complicates the mounting of this roller and generally increases the time required to change between short and long front panel tabs. Most importantly, adjusting the one way clutch roller can only affect a small amount of tape length adjustment.
Control of the tape supply roll is commonly done using a spring leaf mounted stationary on the surface of the hub to hold the inside core of a tape roll. The leaf spring allows flexibility to accommodate a certain variation of core with standard diameter of 3″. Most commonly the tape roll has to be forced in to the hub to secure the tape roll. Some hub comes with an eccentric roller with knurled surface and a small lever to tighten the tape roll. All these locking devise are not sufficient to secure the tape roll. The paper core inside diameter of a large roll usually smaller with tape wound. As the tape roll reduces towards the end, less tape wound around the paper core which starts to loosened and deformed, consequently the leaf spring or knurled surface roller lose their gripping effect and the tape roll slides off the hub.